Bacillus anthracis is a gram-positive, spore-forming bacterium that causes anthrax. It forms irregular, grayish white colonies with a frosted glass appearance on nutrient agar. In humans, it typically causes cutaneous anthrax via skin contact with infected animals. The infection develops from a papule to a vesicle to a pustule and ulcer. Pulmonary anthrax can result from inhaling spores. Diagnosis involves finding gram-positive chains in samples and a purple reaction around bacilli with methylene blue staining. Culture shows medusa head colonies on agar. Anthrax is treated with antibiotics like penicillin and vaccines are used for high-risk groups.

1. RATHEESH R.L
bacillus

2. It is generally classified as
-GRAM POSITIVE BACILLI
-GRAM NEGATIVE BACILLI

3. GRAM POSITIVE BACILLI
1. BACILLUS
2. CORNEY BACTERIUM
3. CLOSTRIDIUM
4. MYCOBACTERIUM

4. GRAM NEGATIVE BACILLI
• IT INCLUDES ENTEROBACTERIA FAMILY AND
VIBRIOS

5. GRAM POSITIVE BACILLI
BACILLUS
The medically important species is
BACILLUS ANTHRACIS

7. MORPHOLOGY
• It’s aerobic G +ve, non motile and non spore
forming.
• Size varies from 4-8 to 1-1.5mm
• They may be arranged in singles or in pairs or
in short chains.

8. CULTURAL CHARACTERISTICS
• They are aerobic and facilitative anaerobic,
grow optimum at the temperature of 37 degree
C, and PH 7.75

9. NUTRIENT AGAR MEDIUM
• colonies will be formed which are irregualar, round,
grayish white colour, froasred glass appearance
measuring 2-3 mm in diameter.
• under microscope the edges of colonies will show
tangled mass of long hair like curls, so it is called
MEDUSA HEAD

11. NUTRIENT BROTH
• It shows floccular turbidity or no turbidity

12. BLOOD AGAR MEDIUM
• NO HEMOLYSIS WILL OCCUR

13. GELATIN STAB CULTURE
• INVERTED FIT TREE APPEARANCE WILL OCCUR

15. PATHOGENESIS
• Anthrax is primarily a disease of domesticated
and wild animals, particularly herbivorous
animals, such as cattle, sheep, horses, and goats.
• Humans become infected incidentally when
brought into contact with diseased animals,
which includes their flesh, bones, hides, hair and
excrement.

16. • The most common form of the disease in
humans is cutaneous anthrax, which is usually
acquired via injured skin or mucous
membranes.
• A minor scratch or abrasion, usually on an
exposed area of the face or neck or arms, is
inoculated by spores from the soil or a
contaminated animal.

17. • The spores germinate, vegetative cells
multiply, and a characteristic gelatinous
edema develops at the site.
• This develops into papule within 12-36 hours
after infection.
• The papule changes rapidly to a vesicle, then a
pustule (malignant pustule), and finally into
a necrotic ulcer from which infection may
disseminate, giving rise to septicemia.

18. • Another form of the disease, inhalation /
pulmonary anthrax (woolsorters' disease),
results most commonly from inhalation of
spore-containing dust where animal hair or
hides are being handled.
• The disease begins abruptly with high fever
and chest pain.

19. • Gastrointestinal anthrax :
• Intestinal anthrax results from the ingestion of
poorly cooked meat from infected animals.
Gastrointestinal anthrax is rare but may occur
as explosive outbreaks associated with
ingestion of infected animals.
• It is manifested by diarrhea and malena

20. LABORATORY DIAGNOSIS
It mainly includes
1. hematological investigations and
2. bacteriological investigations

21. HEMATOLOGICAL INVESTIGATIONS
• It shows an increase in the leucocyte count.

22. BACTERIOLOGICAL INVESTIGATIONS
• The specimen is collected depending upon the
nature of infection.
• Swabs, pus from pustules, blood in
septicemia, sputum in pulmonary anthrax,
gastric aspirates, feces or food in intestinal
anthrax.

23. MICROSCOPY
• After gram staining under microscope it shows
gram positive bacilli in chains
• When the blood films are stained with
polychrome methylene blue for 5-10 seconds ,
it shows a purplish material around the bacilli.
• It is a characteristic feature of B.anthracis and
is known as Mc Fadyean’s reaction.

24. CULTURE
• The specimen is inoculated in nutrient agar
medium or blood agar medium at 37 degree C
for 12-24 hrs , medusa head colonies will
appear.
• Gelatin stab culture: shows inverted fit tree
appearance

25. BIO CHEMICAL TESTS
• 1. SUGAR FERMENTATION TEST: PRODUCTION
OF ACID ONLY
• 2. CATALASE TEST: POSITIVE
• 3. NITRATE REDUCTION TEST : POSITIVE
• 4. GELATIN LIQUEFACTION TEST: POSITIVE

26. ANIMAL INOCULATION TEST
• In this test a small amount of exudate is
injected s/c into the guinea pig or mouse.
• The animal dies within 40-72 hrs shows the
presence of B.anthracis.

27. SEROLOGICAL TESTS
• Infected tissue is washed with saline and
boiled for 5minutes and filtered.
• The filtrate is layered over anthrax anti-serum
in a narrow test tube
• If the filtrate contains anthrax antigen, a ring
appearance will occur in the test tube.

28. TREATMENT
• The drug includes
– Penicillin
– Ciprofloxacin
– Streptomycin
– tetracycline

29. VACCINES
• Salvo’s immune serum is used in serious toxic
cases
• Cell free vaccine used in high risk groups
• Non-living vaccine is using among agricultural
workers.